Because a small number of Protestants and Restorationists are exercising their right to debate with a combined ecumenical group of Eastern and Oriental Orthodox, Protestants and Roman Catholics all of whom are committed to the doctrine of the Third Ecumenical Synod held in Ephesus in 433 AD regarding their issue, and this is good, because it provides a fellowship opportunity for the two sides and stimulates learning. It also helps us recall scriptural verses and creates a mutual reason to read Sacred Scripture. Finally it allows for the alliance of traditional Protestants, Orthodox and Catholic Christians to propagate knowledge about the Councils of Ephesus and Chalcedon and the nature of Nestorianism, and why it is important that it be rejected as an error.
That being said, the discussion has been sidetracked by people needlessly attacking the Ecumenical Councils rather than seeking to get to the truth of the matter being discussed, which I find somewhat frustrating. Because the Ecumenical Councils exist; you don’t have to agree with them, but the real issue that we should be discussing is whether or not John MacArthur violated the theological degrees and canons of the Council of Ephesus or the Council of Chalcedon.
Now, while Nestorius was a pompous heresiarch, as I said earlier I cannot accuse John MacArthur as a fellow Nicene Christian of heresy, but I can say that he has made the mistake of many people who become, in my view, overly concerned about veneration of the Theotokos, and made the Christological error by expressing the Nestorian denial of the status of the Blessed Virgin Mary as the Mother of God. Now, I do regard it as being borderline acceptable based on the literal texts of the Councils if one rejects the phrase “Mother of God” but confesses that St. Mary is Theotokos, but as far as I am aware he has not done that, nor has he, to my knowledged, professed agreement with the Councils of Ephesus or Chalcedon, but if you or someone else finds out that he has declared agreement with the third or fourth ecumenical council, then he has merely made a contradictory statement, and if he has acknowledged the status of St. Mary as Theotokos, he has made no error at all. I am going to be looking into this aspect shortly in an attempt to determine what John MacArthur actually did.